Project Summary: The aim of this study is to validate the novel technical application of flow cytometry and cell sorting combined with molecular analysis to detect and to confirm low levels of disease in hematologic malignancies. Combining standard flow cytometry and standard molecular analysis protocols can provide a highly sensitive and specific tool for disease detection and confirmation in diagnostic, staging and monitoring leukemia, myeloma and lymphoma specimens. Detection of minimal residual disease (MRD) can be crucial to assess risk of relapse and for determining those patients who may benefit from therapy reduction or intensification. This study will use existing diagnostic or monitoring patient specimens from leukemia, myeloma, lymphoma and myeloproliferative disorder patients in titration experiments to optimize technical parameters for a quantitative 2-step protocol to identify minimal disease with high sensitivity and specificity. Unfractionated specimens and flow cytometry sorted cell populations will be analyzed by standard molecular analysis protocols as indicated by the disease (Clonality profiling using gene rearrangement analysis for B-and T-cell leukemias and lymphomas; JAK2 point mutation for myeloproliferative disorders; FLT3 mutation analysis for AML; c-kit point mutation for mast cell disorders). This new approach of integrating 2 technologies allows genotypic confirmation of an aberrant population detected and purified by immunophenotype to increase diagnostic certainty. In addition, this new approach can lower sensitivity limits to detect MRD by using standard flow cytometry and molecular analysis protocols down to 1 in 100,000 cells (0.01%). This sensitivity limit can otherwise be achieved only by patient specific real-time PCR assays, which have to be designed retrospectively and their application is too labor-intensive for routine laboratory use. Minimal residual disease detection using patient specific molecular assays has recently been shown in retrospective studies to provide crucial prognostic information for predicting clinical outcome in leukemia patients. Project Narrative: This novel technical development will increase the sensitivity and specificity for detecting and confirming minimal disease in hematologic malignancies. More than 100,000 new leukemia, lymphoma and myeloma cases will be diagnosed in the US just in 2005. Significant improvement of diagnostic detection limits and diagnostic confidence will benefit early detection, accurate disease response to specific therapy (monitoring), prognosis and consequently can positively impact treatment success. [unreadable] [unreadable] [unreadable]